This week continues the theme of skin problems and more specifically skin tumours in dogs and cats. Having generally discussed last week what is looked for when examining an animal and the diagnostic steps used, we now focus on common benign lumps you may see. A benign lump is generally one which is well circumscribed (has a definite border), is not locally invasive and does not spread elsewhere.
Firstly we will discuss small wart-like masses called Papillomas. They are caused by a virus and generally grow outwards looking a bit sea anemone or cauliflower-like in appearance. They are usually seen in young dogs most commonly around the mouth or eyes and you would expect them to spontaneous regress (disappear) on their own. They can cause problems if excessive in number or if their position means they rub on the eye or irritate the mouth. Especially in an older animal you should never just assume a lump is just a wart or Papilloma as some other types of tumour can have a similar appearance.
Perianal gland adenomas are the next benign tumour I will mention. As the name suggests, these skin tumours are found around the anal opening and are common in older entire male dogs. They can vary in appearance and can be prone to ulcerating or becoming traumatised. Neutering will cause the majority of these tumours to disappear but usually they are removed at the same time as castration which gets rid of the tumour and hopefully prevents any recurrence. Less commonly you can get a malignant form of this tumour which is why removal and laboratory analysis of the mass (histopathology) is done ideally.
The next masses, Lipomas are extremely common and are basically just fatty lumps. They are usually seen in older dogs and are very soft and freely mobile. If a fine needle aspirate of the mass is done you would expect to find oily fat cells on the microscope slide. The easiest way of describing what they look like once removed is a breast implant as they normally have a definite capsule making them almost like a bag filled with smooth fat. Occasionally on palpation on the animal they can feel firmer usually if buried under layers of muscle. They generally start quite small and some will remain so for life, but removal may be advised if they are in an awkward location, such as under an armpit, as they can get to a very large size and cause a problem just due to occupying the space.
Histiocytomas are small solitary red nodules that usually appear on the extremities of young dogs and are relatively common. They are guilty of being one of the most likely benign tumours to cause panic due to their highly visible and rapidly appearing nature, as well as their ability to ulcerate. They will actually spontaneously regress on their own so technically don’t need to be removed, but often are as it’s as nearly as easy to just excise them as biopsying them to get a definite diagnosis.
Lastly, are sebaceous cysts which are sac-like structure that can fill up over time with a cheesy secretion. They will then burst before cyclically fill up again. They are common in certain breeds and particular individual dogs can be prone to getting great numbers of them. Removal can be done if they are repeatedly becoming infected, are excessive in number or if they are in an awkward location.
Next week we look briefly at malignant skin tumours but it is import to reiterate that it’s impossible to give a definitive diagnosis, or know for certain if a mass is benign or malignant from just looking at or feeling a lump, so even if you suspect a mass your pet has is nothing to worry about it’s always better to get it checked out to be on the safe sound.